Drip trays are widely used in industrial and domestic environments where water condenses. For example, in air conditioning systems and the like, it is usual to provide a drip tray under condensation or refrigeration coils. Condensate falling from the coils is collected in a drip tray which is provided with a drain connected to a water waste system or recirculation system. Other situations in which a drip tray is used are commonplace.
A problem with drip trays is that biofilm grows on wet surfaces in the tray. Excessive biofilm growth can result in the drain becoming blocked which in turn can cause the tray to overflow, and cause flooding.
It has been proposed to treat the water or tray surfaces with biocides to inhibit such growth but such systems have been excessively costly in use. The biocides have been non-oxidizing, and have been provided in tablet form. Since non-oxidising biocides are not wide spectrum, i.e. are not effective against certain genera or strains of biofilm-forming organisms, the efficacy of the biocides is reduced over a period of time. Also the microorganisms present in the environment of the non-oxidising biocide over an extended period give rise to increasing resistance of the microorganism to the biocide. Prior art treatments require the tray to be thoroughly cleaned before use and to date no satisfactory answer to the problem in terms of efficacy, biofilm remediation and bacterial resistance has been found. A further difficulty in many cases relates to the trays not being removable and thus being unable to be cleaned since the clearance between the bottom of the coils and the drip tray is normally too limited to allow clear access.
In commercial air conditioning systems, drip trays are usually located in an air treatment plant of the building—an area with restricted access. Often the trays are positioned at a height of up to 5 m, requiring use of a ladder, and their servicing is done by highly qualified technicians, i.e. expensive and time-consuming. It is not uncommon to find a tray that is serviced once every 12-24 months, if at all.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
It is an object of preferred embodiments of the present invention to provide an improved method for controlling biofilm in a drip tray and its drainage line or the like, and to provide a tablet for use in the method, and a method of manufacture of such tablets.